The invention relates to a drive unit for a vibrating spiral conveyor, consisting of a base part, with which an opposed-action part and a fastening part, the motion of which is coupled with that of a pot, are connected flexibly, the former over several first leaf spring elements and the latter over several second leaf spring elements, it being possible to bring the opposed-action part and the fastening part into an opposite, torsionally vibrating movement about a central axis of rotation.
Vibrating, spiral conveyors serve to convey and, optionally, orient small components, which are brought, as a disordered quantity, into the conveyor pot. At the inner surface of the conveyor pot, a peripheral conveyor helix is provided, along which the smallest components are moved forwards by micro-throws during the operation, during which the pot vibrates at a high frequency. A vibrating spiral conveyor with a drive unit of the type in question here is known, for example, from EP 0 644 134 B1. The drive unit, described there, has a base part, over which it and, with it, the vibrating spiral conveyor are fastened to a machine table or a machine frame, rubber buffers being interposed. During operation, parts, vibrating opposite to one another, are connected over appropriate leaf spring elements with the base part, namely, on the one hand, an opposed-action part, which is connected flexibly with the base part over several first leaf spring elements, and, on the other, a fastening part, which is coupled flexibly over several second leaf spring elements with the base part. The opposite movements of the parts is brought about by a drive device, acting between them, as a rule, an electromagnetic drive device with a magnetic core, which is fastened especially at the opposed-action part, and a magnet armature, which is disposed at the fastening part.
The possibility of moving both parts relative to one another and relative to the base is ensured, as described, over the respective leaf spring elements. For drive units of the type in question, the leaf spring elements are disposed distributed about the central axis of rotation. Admittedly, by this construction, appreciable damping of interfering vibrations, introduced into the base part and passed on by the latter to the machine frame, can be achieved because of the equalization of vibrational forces due to the oppositely vibrating masses. However, during prolonged operation and, with that, fatigue loading of the leaf spring elements, damage to the leaf spring elements up to breakage of the springs has resulted from the stress on the springs. Frequently, in spite of the similar construction of the drive units and of the assembled vibrating spiral conveyors, a uniform vibrating behavior could not be observed. This means that there is a relative large scatter in the vibrating behavior of the individual units. Finally, the conveying speeds of vibrating spiral conveyors of similar construction were frequently also different.
The invention is therefore based on the problem of indicating a drive unit, which is an improvement by comparison and permits a reliable and homogeneous vibrating behavior.